The present invention relates to a rocker valve for internal combustion engines. More specifically, the invention relates to a retaining mechanism for coupling the rocker arm of the rocker valve to its support element.
Ball and socket rocker valves are common in valve drive devices which require systematic opening and closing of the valve. The rocker valves generally employ a rocker lever, which is movably pivoted by a cam, to drive a valve ball within its support element. Typically, the support element is a complementary spherical socket. The retention of the socket to its valve ball is a common concern for the design of these types of rocker valves. The use of a securing device to retain the socket to its valve ball is a general solution.
Metal clips, stampings, and wire forms are common forms of securing devices. These devices engage a part of the support element on the one hand and the valve ball on the other hand to establish a positive connection between the support element and the valve ball. For instance, U.S. Pat. No. 1,521,623 to Hendrickson teaches a valve mechanism using a securing device constructed of a strip of sheet metal to maintain the seated position of a valve ball within a ball seat. Hendrickson""s valve mechanism includes a rocker lever having a shaped cavity for engaging the valve ball, a push rod having a ball seat defined at one end, and the valve ball resting loosely on the ball seat and under the shaped cavity. The lower end of the strip of sheet metal is clamped to the push rod, the upper end of which is bent over the rocker arm, preventing it from getting too far away from the ball. However, because there is a potential that the loose valve ball may fall out of its seat, this design is not suitable for installation on valve mechanisms that may be subjected to tilting.
An example of a securing device of a rocker valve assembly which incorporates a metal wire clip to hold a valve ball (not shown) and its support socket together is shown in FIGS. 1-3. As shown in FIG. 1, this prior art design employs an interior groove concept where the support socket 20 is provided with a wire clip groove 21 on the interior surface of support socket 20 for receiving a wire clip 22. Support socket 20 further includes a valve ball cavity 23 configured to receive and support the valve ball. As shown in FIGS. 2 and 3, wire clip 22 is in the form of an irregular ring having the two open ends 24 and 25 overlapping each other and enclosing an aperture 26. In its natural, unloaded state, wire clip 22 has an outside dimension that is configured to be retained within wire clip groove 21 and aperture 26 has, at its widest dimension, a width A which is smaller than the largest diameter (fullest circumference) of the valve ball. During assembling of the securing device, wire clip 22 is installed first into wire clip groove 21 and then the valve ball is inserted through aperture 26 into valve ball cavity 23. When the valve ball is pushed against aperture 26, open ends 24 and 25 slide apart enlarging aperture 26 and allowing passage of the valve ball beyond its fullest circumference; when the pressure is relaxed, open ends 24 and 25 spring back restoring the natural, unloaded dimension of aperture 26 and capturing the valve ball in ball cavity 23. Installation of wire clip 22 into wire clip groove 21 of support socket 22 may be done with automated equipment. However, because interior wire clip groove 22 is located inside support socket 20 and is hidden from view, especially when installation is performed with automated equipment, it is not easy to determine whether wire clip 22 is correctly and fully inserted in wire clip groove 21. Improper installation of wire clip 22 has contributed to many cases of missing support socket 20 from the rocker valve assembly. In addition, this interior groove design is costly to machine and requires complicated equipment to assemble the components.
A different style of securing device has been disclosed in U.S. Pat. No. 5,775,280 to Schmidt, et. al. Schmidt teaches a valve control mechanism including a support member with a spherical end which is received in a concave recess (socket) of a finger lever. The finger lever is secured onto the support member by a plastic retention cap. The retention cap appears to be retained by interference fit around the periphery of the concave recess. However, it is known that interference fit is prone to unexpected separation, so this securing device is not suitable for many applications where the valve mechanisms may be subjected to pulling forces.
It may be appreciated, therefore, that there is a need for a new and improved securing device which can reliably and securely hold the valve ball and socket of a rocker valve together, the assembly of which is simple and conducive to automated assembly methods.
The present invention discloses a securing device having mechanical interlocking features for the retention of a rocker lever ball socket on a rocker lever ball of a rocker valve assembly. In particular, the rocker valve assembly includes a rocker lever with a valve ball attached thereto that engages a socket having a spherical pocket which receives the valve ball. The socket is provided with a groove on its outer diameter and the retaining cap is provided with inward protruding tabs on its inner diameter. In an assembled configuration, the tabs interlock within the groove thereby retaining the retaining cap in the socket. The retaining cap includes a circular aperture at one end, allowing the stem of the valve ball to extend out of the socket and be attached to the rocker lever. The dimension of the aperture is sized to be smaller than the full circumference of the valve ball. In one specific embodiment, the retaining cap is constructed of a slightly elastic material so that, during installation, the aperture can be elastically deformed to allow passage of the valve ball and then retracts to its natural, unloaded dimension so that the valve ball is captured within the socket.
One object of the present invention is to provide an improved securing device for retaining a support socket onto a valve ball of a rocker valve assembly.
This and other objects of the present invention will be apparent from the following description of the preferred embodiments.